package com.example.chat.util;

import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import java.time.LocalDateTime;
import java.time.ZoneOffset;
import java.time.format.DateTimeFormatter;

/**
 * 全局唯一id生成
 */
@Component
public class RedisIdWorker {

    /**
     * 开始时间戳
     */
    private static final long BEGIN_TIMESTAMP = 1640995200L;

    /**
     * 序列号位数
     */
    private static final long COUNT_BITS = 32;

    private StringRedisTemplate redisTemplate;

    public RedisIdWorker(StringRedisTemplate redisTemplate){
        this.redisTemplate = redisTemplate;
    }

    /**
     * 获取唯一id
     * @param prefix
     * @return
     */
    public long nextId(String prefix){
        //生成时间戳
        LocalDateTime now = LocalDateTime.now();
        long nowEpochSecond = now.toEpochSecond(ZoneOffset.UTC);
        long timestamp = nowEpochSecond - BEGIN_TIMESTAMP;
        //生成序列号
        String date = now.format(DateTimeFormatter.ofPattern("yyyy:MM:dd"));
        long count = redisTemplate.opsForValue().increment("icr:" + prefix + ":" + date);
        //拼接返回
        return timestamp << COUNT_BITS | count;
    }

}
